Gut bacteria may prevent food allergies

Microbes block food from seeping into bloodstream, mouse study shows

SEAL IT UP Mice lacking certain bacteria in their guts (left) have less intestinal mucus (dark purple specks) than mice harboring Clostridia bacteria (right). The mucus may prevent food allergens from leaking out of the intestines and into the bloodstream.

Peanuts can drive people’s immune systems nuts, but gut microbes could offer some protection. Mice harboring Clostridia bacteria in their guts are less sensitive to the notoriously allergenic legumes than mice without the microbes, researchers report August 25 in the Proceedings of the National Academy of Sciences.

For years scientists have suspected that some gut bacteria curb food allergies, and that killing these good guys could bring trouble. But no one knew which microbes helped or how exactly they worked.

Cathryn Nagler of the University of Chicago and colleagues treated some mice with antibiotics to wipe out the animals’ gut bacteria, and then triggered an allergy-like response to peanut particles. Peanuts revved up the germ-free animals’ immune systems — but mice with normal gut bacteria didn’t have the bad reaction.

Giving germ-free mice a dose of Clostridia bacteria made the animals more like their counterparts with normal gut flora. The microbes encourage mouse cells to make mucus that helps seal up the intestines, keeping food particles from slipping into the bloodstream and riling up the immune system, the researchers found.

Humans also harbor Clostridia, so boosting these bacteria’s numbers with probiotics — living cultures of bacteria in yogurt and other foods — may help prevent or treat food allergies in people, Nagler’s team suggests.